The Anonymous Widower

Would Batteries Help Voltage Change-over In A Dual Voltage Train Or Tram-Train?

Battery Power And Tram-Trains

Consider.

  • The Class 399 tram-trains in Sheffield can work on both 25 KVAC and 750 VDC overhead electrification.
  • Their German cousins in Karlsruhe can work on both 15 KVAC and 750 VDC overhead electrification.

In Karlsruhe, there is a ceramic rod between the two overhead cables with different voltages and the pantograph rides across. I suspect that clever power  electronics on the tram-train measures the voltage and converts it automatically to that needed to power the tram-train.

I haven’t been able to see how Sheffield connects the two different voltages, but I wouldn’t be surprised if a similar system with a ceramic rod is used.

Look at this picture, I took of a Class 399 tram-train in Sheffield.

 

Note the BATTERY CHARGE socket to the left of the car number.

Why would an electrically-powered vehicle need a battery?

I suppose it could be to start up the tram-train in the morning and raise the pantograph.

But could it also be for emergency power, to move the tram-train short distances, such as in depots or to assist the vehicle through the dead sections, where the power supply changes from one voltage to another?

The Class 399 tram-trains ordered for the South Wales Metro will also have to cope with discontinuous electrification. So is the technology needed for this already installed in the tram-trains in Sheffield?

Battery Power And Dual Voltage Trains

Suppose you have a train like a Class 378 or Class 700 train, that can run on both 25 KVAC overhead  and 750 VDC third-rail electrification.

Third-rail trains with contact shoes deal with discontinuous electrification all the time.

If a dual-voltage train had a battery that could take it say two hundred metres, then I believe that voltage changeover could be simplified and speeded up.

I have watched Class 717 trains change voltage at Drayton Park station and what changes would a limited battery capability make.

The third-rail electrification would stop several metres short of the station and would be removed in the station itself.

Going towards Moorgate, this would be the procedure.

  • The train would stop in the station as it does now.
  • The driver would drop the pantograph, whilst passengers unloaded and loaded.
  • The driver would close the doors.
  • The train would accelerate away on battery power.
  • After a few metres the train would contact the third-rail and the train’s computer would change from battery to third-rail power.

Going away from Moorgate, this would be the procedure.

  • The train would automatically disconnect from third-rail power, where that stopped to the South of the station.
  • The train would automatically switch to battery power.
  • The train  would stop in the station as it does now.
  • The driver would raise the pantograph, whilst passengers unloaded and loaded.
  • The driver would close the doors.
  • The train would accelerate away on overhead power.

The stops should be no longer, than a normal station stop without power changeover.

Conclusion

Batteries may well reduce the time taken to change voltage

 

February 19, 2019 Posted by | Energy Storage, Transport | , , , , | 2 Comments

Pan Up And Pan Down At Drayton Park Station

The years and decades go by and the new Class 717 trains, just like their predecessors; the Class 313 trains, continue to change between 25 KVAC overhead and 750 VDC third rail electrification at Drayton Park station.

There appears to have been little noticeable development in the forty years since the Class 313 reains were introduced. But the operation of the Class 717 trains appears smoother and quieter.

I would have thought, that for safety reasons, the new trains would have used battery power between Drayton Park and Moorgate stations.

After all it’s only two and a half miles, that is run using third-rail electrification.

I’d be very interested to see how much power is used by the new Class 717 trains South of Drayton Park.

In Weight And Configuration Of A Class 717 Train, I showed that the kinetic energy of a jam-packed Class 717 train at 85 mph is 56.15 kWh.

  • I doubt that this sort of speed is achieved in the tunnels.
  • At 60 mph, the energy would be 28 kWh
  • At 40 mph, the energy would be just 12 kWh.

Obviously, hotel power for air-conditioning and lights will be needed for the train, but even at 5 kWh per car per mile, that would only be 150 kWh.

To carry 200 kWh of batteries on a six-car train is a very practical proposition.

  • Vivarail have done it in a three-car train.
  • There could be a short length of third-rail electrification to top up the batteries at Moorgate station, if required.
  • Battery power could be used in depots to move trains, which would mean depots could have less electrification.
  • Trains could be moved to the next station, if the electrification should fail.

The route between Moorgate and Drayton Park stations, is probably one of the best and easiest in the UK for battery operation.

January 31, 2019 Posted by | Energy Storage, Transport | , , , | Leave a comment

A Greater Anglia Train In An Unexpected Place

I took these pictures from Drayton Park station of a Greater Anglia train, which  consisted of a Class 90 locomotive, Mark 3 coaches and a DVT going South on the line above the station that leads to the Canonbury Curve.

I wonder what it had been doing?

 

October 1, 2018 Posted by | Transport | , , , | 1 Comment